Intervertebral discs serve several functions. A primary function of the intervertebral disc is to facilitate mobility of the spine. In addition, the disc provides load bearing, load transferring, and shock absorption between vertebral discs. The disc itself is formed of two major components, a gelatinous nucleus pulposus which is surrounded by an annulus fibrosis.
The intervertebral disc can be damaged in many ways. Mechanical damage can be caused by herniation in which a portion of the nucleus projects through an opening or tear in the annulus. Progressive degeneration can be caused by either genetic or biochemical problems. In such situations, there may be a decrease in the internal nucleus volume resulting in a decrease in disc height preventing the disc from performing its designed functions.
One way to relieve the symptoms of a ruptured or deteriorated disc is by surgical removal of a portion or all of the intervertebral disc. Removal of the disc decreases disc height, which can cause a number of severe problems. Therefore, subsequent to removal of the disc, steps must be taken to restore the disc height, or separation, between the adjacent vertebrae. Many attempts have been made to insert either mechanical devices or various polymeric materials that provide solid support between the vertebrae. These devices have had varying degrees of success.
One device that has been utilized to restore disc height is shown in U.S. Pat. No. 6,387,130. The implant includes a C-shaped curve and is placed anterior within the disc space. This implant has several limitations including the use of a plurality of implants to form the curved implant, lack of a mechanism to keep the plurality of implants in plane during placement in the disc space, and lack of an instrument to effectively deliver the implant. Additionally, a number of other implants are available that due to their predetermined C-shaped profile require a significant degree of manipulation during implantation into the disc space. This manipulation may require a larger surgical access opening in the patient as well as an increased opening in the annulus of the disc.